dog, can mean anything from 'close friend' to 'you peice of trash' but it doesn't have to be send to a person of an Afro-American race, it can be said to anyone of anyrace.
dawg (with a 'w'): someone who is rather horny and thinks some dirty thoughts. usually someone of a pretty kinky nature, open-minded about sexual acts and up for experimenting with new things..ie- anal sex, sexual acts in strange places, fone sex every nite, ect.